Could I still be pregnant with a negative urine and blood test?

Patient: Hello, I am having trouble understanding if I could be pregnant or not. I am 20 years old and am on a birth control pill. I have taken home urine tests for the past few weeks and they came back negative. I tried concentrating my urine thinking I could be drinking too much water for it to not detect any. I missed my period and had brown spotting instead. If I am I would be 6 weeks today and last week I started having nausea and vomited once in the morning. I am also noticing that I am very moody lately, crying, tired, have gained weight. I got a blood test yesterday and it came back saying I was not pregnant and that I had less than one hcg. I am wondering if the blood test could be wrong. Also if I am not pregnant why am I having these symptoms? Thank you.

Symptoms: Missed period, brown spotting, nausea, vomiting, clothes fitting tighter, tired, moody and crying, negative urine and blood test

Doctor: The correct time to take a urine test would be around the time your period is expected or better if if it is overdue by a couple of days. So maybe the time you took the tests was not the right time. The blood test done recently indicates that you are not pregnant and maybe a failed pregnancy (blighted ovum) could explain your present symptoms. If the symptoms persist or are bothersome please visit your doctor.